Advances in the Chemistry of α,α'-Disubstituted Pyridines

The methods of synthesis of α,α'-disubstituted pyridines are surveyed and recent advances in this field are indicated. Various ways of constructing the α,α'-disubstituted pyridine ring and of replacing one set of α,α'-substituents by another are described. The characteristics of the chemical behaviour of α,α'-disubstituted pyridines due to the steric and inductive effects of the substituents and their influence on the reactivity of the nitrogen atom and processes involving electrophilic substitution in the pyridine ring are examined. The chemical behaviour of the various functional groups in pyridine systems with α,α'-substituents as well as the characteristic features of the tautomerism and the dual reactivity of substances of this class are discussed.
The bibliography includes 254 references.